Valve operating mechanism for fluid pressure engines, pumps, or compressors



- Feb 1956- H. R. RICARDO 1,897,179

VALVE OPERATING MECHANISM FOR FLUID PRESSURE ENGINES, PUMPS, OR COMPRESSORS Filed May 27, 1930 V J Men/5K,

Patented Fb."-14, 1933 UNITED STATES PATENT ormca HAIRY BALPE RICARDO, OF LONDON, ENGLAND VALVE OPERATING MECHANISM FOR FLUID PRESSURE ENGINES, runs, 03 G'JIPBESSOBS Inflation fled m 27, mo, Serial Io. mass, and 111' Great 3mm lane :5, 1929.

This invention relates to valve operating mechanisms for fluid pressure engines, pumps or compressors, and of the kin comprising a valve, a tappet operating the valve and an adjusting member interposed between the tappet and the valve and capable of being moved to vary the lost motion between these parts, and has for its object to provide an im roved form of mechanism of this type. 10 'Ehe invention is particularlv,'but not exclusively, applicable to the operating mechanism for the valve or valves of a fuel pump of the kind in which the quantity'of fuel injected is varied by controlling the opening period of the valve or valves. Hitherto in such apparatus either a movable fulcrum has been employed for a lever acting as a valve tappet, which arrangement involves mechanical difliculties where the forces involved are considerable, or alternatively an arrangement such as that described in the present appl1- cants prior Letters Patent of the United States of America, No. 1,701,389, dated 5th February, 1929, has been employed in which an adjusting member in the form of a plvoted wedge is interposed between the valve audits tappet and is movable to vary the lost motion between these parts. With this latter arrangement however, when employed on a multi-cylinder engine it is diflicult to operate a number of wedges simultaneously from a common control in a sufliciently rigid manner to ensure a corresponding adjustment of all the valve operating mechanisms and thus a corresponding variation in the quantity of fuel injected into all the cylinders.

According to the present invention mechanism of the above type for varying the opening period of a valve for a fluid pressure engine, pump or compressor comprises in combination withthe valve and a tappet operating this valve, a rotatable member of the nature of a face cam interposed between the valve and the tappet and movable therewith in the: direction of the axis of the cam member, the latter comprising .a curved wedgelike part disposed circumferentially with respect to the axis about which the cam member is rotatable, the cam member being arranged with this wedge-like part between the valve and the tappet so that by rotation of the cam member the lost motion between the tappet and the valve can be varied. I The cam member is conveniently in the form of a disc with the curved wedge-like part on one side thereof, this disc being formed integral with or rigidly connected to a spindle capable of moving axially in a suitable guide in a direction parallel to the axis of the valve and tappet. p

The rotation of the cam member'to vary the lost motion between the tappet and the valve may beefi'ected in various ways. Conveniently, however,\ a gear pinionis either formed on the cam i ember or socoupled to it as to permit relaiiiveaxiahbut not rotational movement between the cam member and the gear wheeli this gear wheel being engaged by a sliding rack whereby it can be rotated and thus cause rotation of the cam member to vary the lost motion between the tappet and valve. -Preferably the rack is constituted by a rod or drum of circular cross-section having a screwthread formed thereon which constitutes the teeth of the rack so that in addition to the normal adjustment of the cam member efiected by moving the rack axially. a fine adjustment can be obtained by rotating the rack.

Such an arrangement is particularly applicable to fuel injection apparatus of the type referred to above for a multi-cylinder internal combustion engine wherein the fuel is injected into each cylinder' by a separate pump plunger having associated therewith 35 one or more suction or spill valves contr lling the quantity of fuel injected and in this case, the racks controlling the cam members between the tappets and valves associated with the individual pump plungers are conveniently arranged end to end and coupled together so as to be movable by a common control member. the connection between adjacent racks being such that the racks can be rotated relatively to one another so as to permit of an individual fine adjustment of the setting of each cam member and thereby ensure that all the pumps will deliver substantially the same quantity of fuel to their respective cylinders for any given setting of the main control member acting on the racks.

In some cases instead of the gear Wheel for rotating the cam member being engaged by a rack as described above, it may be engaged by a worm on a rotatable member so that rotation of such member causes rotation of the gear wheel and cam, means being provided in some cases for adjusting the setting of the member carrying the worm relatively to the gear wheel by moving the member carrying the worm a small distance longitudinally relatively to the member operating it or to other similar worm members engaging gear wheels for rotating the corresponding cam members for controlling the opening period of the valves of adjacent fuel pumps.

The invention may be carried into practice in various ways but one construction according to this invention as applied to a fuel pump for supplying fuel to an internal combustion engine is illustrated by way of example in the accompanying drawing, in which v Figure 1 is a sectional side elevation, and

' Figure 2 is a view of part of the apparatus in the direction of the arrow shown in Figure 1.

In the construction illustrated the fuel pump comprises a casing A having mounted within it a cylinder B within which operates a plunger C. The lower end of the plunger is connected to a crosshead C which is coupled by a connecting rod C to a triangular lever D which is pivoted at D? and is adapted to have rocking movementimparted thereto about its pivot so as to reciprocate the plunger C.

Leading from the pressure chamber E of the pump is a fuel delivery passage E through which fuel can pass to the. sprayer. The pressure chamber E also communicates through a port E with a passage E leading to a tank or other source of fuel supply (not shown). The port E is controlled by a poppet valve F provided with a spring F tending to maintain it always closed. and with adjusting nuts F for varying the effective length of the 'valve stem. The valve F is adapted to be operated by a tappet G operating within a guide G and controlled by a\ spring G which tends to maintain the lower end G of the tappet always in engagement with a rocking cam member H pivot-ed at D and provided with an arm H whereby rock-' ingmovement can he imparted to the cam.

The triangular lever D and the cam H are adapted to be operated for example by mech anism similar to that described in-the specification of the present applicants copendinsl application for Letters Patent of the United States of America Serial No. 456.237. filed May 27, 1930 so that the valve F is maintained open during the earlier and later portions of each delivery stroke of the pinup plunger C so as to render thesev portionstof the stroke inoperative whereby only the middle portion of the pump delivery stroke when the plunger C is moving rapidly is effective to cause delivery of fuel.

In order to vary the period of opening of the valve F and hence the quantity of fuel injected on each pump delivery stroke,' a valveadjusting-apparatus according to this invention is interposed between the tappet and the valve stem. This apparatus comprises a member J or the nature of a face cam having a wedge-like rim J, the thickness of which varies at different circumferential parts thereof. The opposite faces of this rim are adapted to engage respectively with the tappet G and valve F. From the lower face of the disc J extends a rod-like guide member K sliding freely in a tubular socket K" the axis of which is parallel to the axis of the valve F and tappet G. Surrounding the socket K is a gear wheel K of the nature of a worm wheel rigidly connected to which is a boss K having a projection K which engages with a radial groove K in the disci J.

Engaging with the gear wheel K 'is a rack L in the form of a worm mounted upon a shaft L which is capable of being moved longitudinally in bearing supports L It will be seen that with the arrangement above described longitudinal movement of the shaft L will act through the worm'L. gear wheel K and member K to cause rotation of the disc J so as to vary the portion of the rim J 1 thereof which lies between the tappet and valve, whereby the effective clearance between these parts and hence the period of opening of the valve and the quantity of fuel injected on each pum delivery stroke can be controlled. I11 ad ition it'will be seen.

that "by rotating the shaft L the worm-like rack member will act after the manner of a worm to cause a fine adjustmentof the.

disc J.

The invention is particularly applicable to fuel supply apparatus of the type described for multi-cylinder engines in which the corresponding valves of all the fuel pumps are adapted to be simultaneously adjusted to control the quantity of fuel injected'into all the cylinders, and in this case each worm-like rack L is conveniently'mounted upon a separate shaft length L the shaft lengths being arranged end to end and connected together so that they can all be moved by a single control member to vary simultaneously the quantity of fuel injected into all the cylinders. In this case the connection between the adj acent shaft lengths L is conveniently such that these shaft lengths with their rackscan be rotated relatively to one another and locked in the desired relative rotational position. Thus the adjacent ends of the shaft lengths may be arranged as indicated in Figure 2 with a member connecting them together comprising parallellinks L coupled to the assure- I shaft lengths L b ins L passin thro h the links and the h aift len g ug able theshaft lengths to be rotated relative to one another throu h 180 or any multiple 8 thereof and to be loc ed in their positions of relative adjustment. Further each worm L is preferab y mounted on its shaft L so as to enable the worm to be rotated relatively to the shaft and locked in any desired rotational position thereon. Thus the worm L is conveniently formed on a sleeve L which can be rotated on the shaft L and clamped thereto frictionally b a nut L acting on one end of the sleeve an forcing it into contact with a second sleeve L ri idly mounted on the other end of the shaft E The nut L, as shown, convenientlv enga es a screwthreaded member L' which is rigidly connected to the shaft L by a pin L. This arrangement enables a fine adjustment of the settings of the various cam members J relatively to one another to be obtained so as to ensure that for a iven setting of the main control acting on a l the racks all the valves will be similarly operated and hence all the fuel pumps will deliver a similar quantity of fuel to their respective I cylinders.

It is to be understood that the arrangement more particularly described above with reference to the drawing is 'ven by way of example only and that the orm of each cam member for controlling the opening period of a valve and the manner in which such cam member is rotated as well as other details of construction may vary without departing from this invention.

What I claim as my invention and desire to secure by Letters Patent is 1. Mechanism for adjusting the clearance bination a rotatable member of the nature of a face cam having thereon a curved wedgelike part disposed circumferentially with respect to the axis about which the cam member can rotate and ada ted to be interposed between the tappet an valve, this rotatable member being movable in the axial direction with the valve and tappet, a gear wheel rotatable with the cam member, a rack engaging the gear wheel and formed as a worm on a rotatable shaft, means for moving the worm shaft longitudinally so as to rotate the cam member and thereby adjust the position of the wedge-like part between the tappet and valve, and means whereb the worm shaft can be rotated while being eld against movegths so as to enbetween a valve and tappet including in comvalve and havin thereona curved wed elike part adapte to be disposed between t e tappet'and valve and circumferentially with respect to the axis about which the cam member can rotate, each rotatable cam member being movable in the axial direction with its valve and tappet, a gear wheel disposed co axially and rotatable with each cam member, a series of sliding racks respectively engaging the gear wheels and arranged end to end, each rack being, in the form of a worm on a rotatable worm shaft, means for connecting the adjacent ends of the worm shafts together in a manner permitting relative rotational adjustment between the worm shafts, and means for imparting longitudinal move ment simultaneously to all the worm shafts.

3. Mechanism for adjusting simultaneously the clearance between the tappets and valves of a number of fuel pumps so as to control simultaneously the uantities of fuel delivered respectively by suc fuel pumps, including in combination a rotatable member of the nature of a face cam associated with each valve and having thereon a curved wedge-like part adapted to be disposed between the tappet and valve and circumferentially with respect to the axis about which the cam member can rotate, each rotatable cam member being movable in the axial direction with its valve and tappet, a gear wheel disposed coaxially and rotatable with each cam member, a series of sliding racks arranged end to end and each en gmg one of the gear wheels, means for positively con nectlng together the adjacent ends of the racks, means for effecting ositive individual ad ustment as between a jacent racks, and means for-imparting longitudinal movement simultaneously to all the racks.

In testimony whereof I have signed my name to this specification.

HARRY RALPH RICARDO.

ment in the axial direction so as to effect a fine adjustment of the cam member.

2. Mechanism for adjusting simultaneously the clearance between the tappets and valves of a number of fuel pumps so as to control simultaneously the quantities of fuel delivered respectively by such fuel pumps, ineluding in combination a rotatable member of the nature of a face cam associated with each 

